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United States Patent | 5,086,387 |
Arroyo ,   et al. | February 4, 1992 |
A clocking circuit connected to a processor for regulating processor operation and including a control circuit that produces a clock signal at a first frequency or for producing a clock signal at a designated one of a plurality of other selectable frequencies in response to a change signal from the processor. The control circuit is connected to a designating circuit that provides a signal to the control circuit to designate one of the selectable frequencies. In the preferred embodiment, the clocking circuit includes a register addressable by the processor and a frequency generator that generates several signals having unique frequencies. The processor may designate one of the frequencies as the clocking frequency by providing the appropriate data to the register. Upon the occurrence of an external event such as a DMA request or an interrupt, the control circuit will provide the clocking signal at a predetermined frequency.
Inventors: | Arroyo; Ronald X. (Elgin, TX); Hanna; James T. (Austin, TX) |
Assignee: | International Business Machines Corporation (Armonk, NY) |
Appl. No.: | 203586 |
Filed: | May 27, 1988 |
Current U.S. Class: | 713/501; 327/145; 713/322 |
Intern'l Class: | G06F 001/04 |
Field of Search: | 364/200 MS File,900 MS File,707 307/269 328/62 |
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Foreign Patent Documents | |||
60-19223 | Jan., 1985 | JP. |
"Designing with the 80C88--A Fully Static CMOS Processor", 8181 New Electronics, 17, (1984), Jul., No. 14, Warley, West Midlands, Great Britain. "80C88 CMOS 8/16 Bit Microprocessor". Japanese Patent Abstract No. 60-19223 entitled "Data Processor". "CMOS Micros Enter the Mainstream" in Computer Design, vol. 23, No. 6, Jun., 1984. "Eight-Bit CMOS Microcomputer Unit Ideal for Intellient Telephone Systems", printed in the A Mini-Micro Conference Record, May, 1984. |